Heat half butter in saucepan. Add sorrel and stir with wooden spoon over a mod high heat until leaves have wilted and any liquid evaporated. In a small bowl, mix flour, cream and egg yolks. Stir into the sorrel. Cook gently stirring for about 3 minutes until lightly thickened, but do not allow to boil. Add the salt/pepper to your taste.

Serve with seasonal vegetables: runner beans, courgette, French beans

Place half the sorrel mix in the dish. Lay the fish fillets on top. Sprinkle with salt and pepper and pur over the remaining sorrel mixture. Dot top with teh remaining butter and bake for approx 20 minutes until fish flakes easily when tested with point of knife.